Move Away from 'drawing' Towards Subclassing LineFragmentView

Author: thecoolwinter

Sources/CodeEditTextView/Extensions/NSRange+/NSRange+init.swift

@@ -7,7 +7,7 @@
 
 import Foundation
 
-extension NSRange {
+public extension NSRange {
     @inline(__always)
     init(start: Int, end: Int) {
         self.init(location: start, length: end - start)

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager+Layout.swift

@@ -19,7 +19,9 @@ extension TextLayoutManager {
     // MARK: - Layout Lines
 
     /// Lays out all visible lines
-    func layoutLines(in rect: NSRect? = nil) { // swiftlint:disable:this function_body_length
+    /// - Warning: This is probably not what you're looking for. If you need to invalidate layout, or update lines, this
+    ///            is not the way to do so. This should only be called when macOS performs layout.
+    public func layoutLines(in rect: NSRect? = nil) { // swiftlint:disable:this function_body_length
         assertNotInLayout()
         guard let visibleRect = rect ?? delegate?.visibleRect,
               !isInTransaction,
@@ -185,11 +187,37 @@ extension TextLayoutManager {
         for lineFragment: TextLineStorage<LineFragment>.TextLinePosition,
         at yPos: CGFloat
     ) {
-        let view = viewReuseQueue.getOrCreateView(forKey: lineFragment.data.id)
+        let view = viewReuseQueue.getOrCreateView(forKey: lineFragment.data.id) {
+            renderDelegate?.lineFragmentView(for: lineFragment.data) ?? LineFragmentView()
+        }
+        view.translatesAutoresizingMaskIntoConstraints = false
         view.setLineFragment(lineFragment.data)
-        view.renderDelegate = renderDelegate
         view.frame.origin = CGPoint(x: edgeInsets.left, y: yPos)
         layoutView?.addSubview(view)
         view.needsDisplay = true
     }
+
+    /// Invalidates and prepares a line position for display.
+    /// - Parameter position: The line position to prepare.
+    /// - Returns: The height of the newly laid out line and all it's fragments.
+    package func preparePositionForDisplay(_ position: TextLineStorage<TextLine>.TextLinePosition) -> CGFloat {
+        guard let textStorage else { return 0 }
+        let displayData = TextLine.DisplayData(
+            maxWidth: maxLineLayoutWidth,
+            lineHeightMultiplier: lineHeightMultiplier,
+            estimatedLineHeight: estimateLineHeight()
+        )
+        position.data.prepareForDisplay(
+            displayData: displayData,
+            range: position.range,
+            stringRef: textStorage,
+            markedRanges: markedTextManager.markedRanges(in: position.range),
+            breakStrategy: lineBreakStrategy
+        )
+        var height: CGFloat = 0
+        for fragmentPosition in position.data.lineFragments {
+            height += fragmentPosition.data.scaledHeight
+        }
+        return height
+    }
 }

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager+ensureLayout.swift

@@ -117,18 +117,20 @@ public class TextLayoutManager: NSObject {
     ///   - wrapLines: Set to true to wrap lines to the visible editor width.
     ///   - textView: The view to layout text fragments in.
     ///   - delegate: A delegate for the layout manager.
-    init(
+    public init(
         textStorage: NSTextStorage,
         lineHeightMultiplier: CGFloat,
         wrapLines: Bool,
         textView: NSView,
-        delegate: TextLayoutManagerDelegate?
+        delegate: TextLayoutManagerDelegate?,
+        renderDelegate: TextLayoutManagerRenderDelegate? = nil
     ) {
         self.textStorage = textStorage
         self.lineHeightMultiplier = lineHeightMultiplier
         self.wrapLines = wrapLines
         self.layoutView = textView
         self.delegate = delegate
+        self.renderDelegate = renderDelegate
         super.init()
         prepareTextLines()
     }

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager.swift

@@ -20,10 +20,11 @@ public protocol TextLayoutManagerRenderDelegate: AnyObject {
         markedRanges: MarkedRanges?,
         breakStrategy: LineBreakStrategy
     )
-    func drawLineFragment(fragment: LineFragment, in context: CGContext)
+
+    func lineFragmentView(for lineFragment: LineFragment) -> LineFragmentView
 }
 
-extension TextLayoutManagerRenderDelegate {
+public extension TextLayoutManagerRenderDelegate {
     func prepareForDisplay( // swiftlint:disable:this function_parameter_count
         textLine: TextLine,
         displayData: TextLine.DisplayData,
@@ -41,7 +42,7 @@ extension TextLayoutManagerRenderDelegate {
         )
     }
 
-    func drawLineFragment(fragment: LineFragment, in context: CGContext) {
-        fragment.draw(in: context, yPos: 0.0)
+    func lineFragmentView(for lineFragment: LineFragment) -> LineFragmentView {
+        LineFragmentView()
     }
 }

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManagerRenderDelegate.swift

@@ -12,6 +12,7 @@ import CodeEditTextViewObjC
 /// fragments, and any lines that need to be broken due to width constraints will contain more than one fragment.
 public final class LineFragment: Identifiable, Equatable {
     public let id = UUID()
+    public let documentRange: NSRange
     public var ctLine: CTLine
     public var width: CGFloat
     public var height: CGFloat
@@ -23,13 +24,15 @@ public final class LineFragment: Identifiable, Equatable {
         scaledHeight - height
     }
 
-    public init(
+    init(
+        documentRange: NSRange,
         ctLine: CTLine,
         width: CGFloat,
         height: CGFloat,
         descent: CGFloat,
         lineHeightMultiplier: CGFloat
     ) {
+        self.documentRange = documentRange
         self.ctLine = ctLine
         self.width = width
         self.height = height

Sources/CodeEditTextView/TextLine/LineFragment.swift

@@ -8,44 +8,38 @@
 import AppKit
 
 /// Displays a line fragment.
-final class LineFragmentView: NSView {
-    private weak var lineFragment: LineFragment?
+open class LineFragmentView: NSView {
+    public weak var lineFragment: LineFragment?
 
-    weak var renderDelegate: TextLayoutManagerRenderDelegate?
-
-    override var isFlipped: Bool {
+    open override var isFlipped: Bool {
         true
     }
 
-    override var isOpaque: Bool {
+    open override var isOpaque: Bool {
         false
     }
 
-    override func hitTest(_ point: NSPoint) -> NSView? { nil }
+    open override func hitTest(_ point: NSPoint) -> NSView? { nil }
 
     /// Prepare the view for reuse, clears the line fragment reference.
-    override func prepareForReuse() {
+    open override func prepareForReuse() {
         super.prepareForReuse()
         lineFragment = nil
     }
 
     /// Set a new line fragment for this view, updating view size.
     /// - Parameter newFragment: The new fragment to use.
-    public func setLineFragment(_ newFragment: LineFragment) {
+    open func setLineFragment(_ newFragment: LineFragment) {
         self.lineFragment = newFragment
         self.frame.size = CGSize(width: newFragment.width, height: newFragment.scaledHeight)
     }
 
     /// Draws the line fragment in the graphics context.
-    override func draw(_ dirtyRect: NSRect) {
+    open override func draw(_ dirtyRect: NSRect) {
         guard let lineFragment, let context = NSGraphicsContext.current?.cgContext else {
             return
         }
 
-        if let renderDelegate {
-            renderDelegate.drawLineFragment(fragment: lineFragment, in: context)
-        } else {
-            lineFragment.draw(in: context, yPos: 0.0)
-        }
+        lineFragment.draw(in: context, yPos: 0.0)
     }
 }

Sources/CodeEditTextView/TextLine/LineFragmentView.swift

@@ -41,7 +41,7 @@ public final class TextLine: Identifiable, Equatable {
     ///   - stringRef: A reference to the string storage for the document.
     ///   - markedRanges: Any marked ranges in the line.
     ///   - breakStrategy: Determines how line breaks are calculated.
-    func prepareForDisplay(
+    public func prepareForDisplay(
         displayData: DisplayData,
         range: NSRange,
         stringRef: NSTextStorage,
@@ -52,6 +52,7 @@ public final class TextLine: Identifiable, Equatable {
         self.maxWidth = displayData.maxWidth
         typesetter.typeset(
             string,
+            documentRange: range,
             displayData: displayData,
             breakStrategy: breakStrategy,
             markedRanges: markedRanges
@@ -65,8 +66,14 @@ public final class TextLine: Identifiable, Equatable {
 
     /// Contains all required data to perform a typeset and layout operation on a text line.
     public struct DisplayData {
-        let maxWidth: CGFloat
-        let lineHeightMultiplier: CGFloat
-        let estimatedLineHeight: CGFloat
+        public let maxWidth: CGFloat
+        public let lineHeightMultiplier: CGFloat
+        public let estimatedLineHeight: CGFloat
+
+        public init(maxWidth: CGFloat, lineHeightMultiplier: CGFloat, estimatedLineHeight: CGFloat) {
+            self.maxWidth = maxWidth
+            self.lineHeightMultiplier = lineHeightMultiplier
+            self.estimatedLineHeight = estimatedLineHeight
+        }
     }
 }

Sources/CodeEditTextView/TextLine/TextLine.swift

@@ -11,6 +11,7 @@ import CoreText
 final public class Typesetter {
     public var typesetter: CTTypesetter?
     public var string: NSAttributedString!
+    public var documentRange: NSRange?
     public var lineFragments = TextLineStorage<LineFragment>()
 
     // MARK: - Init & Prepare
@@ -19,10 +20,12 @@ final public class Typesetter {
 
     public func typeset(
         _ string: NSAttributedString,
+        documentRange: NSRange,
         displayData: TextLine.DisplayData,
         breakStrategy: LineBreakStrategy,
         markedRanges: MarkedRanges?
     ) {
+        self.documentRange = documentRange
         lineFragments.removeAll()
         if let markedRanges {
             let mutableString = NSMutableAttributedString(attributedString: string)
@@ -62,6 +65,7 @@ final public class Typesetter {
             // Insert an empty fragment
             let ctLine = CTTypesetterCreateLine(typesetter, CFRangeMake(0, 0))
             let fragment = LineFragment(
+                documentRange: NSRange(location: (documentRange ?? .notFound).location, length: 0),
                 ctLine: ctLine,
                 width: 0,
                 height: estimatedLineHeight/lineHeightMultiplier,
@@ -107,7 +111,9 @@ final public class Typesetter {
         var leading: CGFloat = 0
         let width = CGFloat(CTLineGetTypographicBounds(ctLine, &ascent, &descent, &leading))
         let height = ascent + descent + leading
+        let range = NSRange(location: (documentRange ?? .notFound).location + range.location, length: range.length)
         return LineFragment(
+            documentRange: range,
             ctLine: ctLine,
             width: width,
             height: height,

Sources/CodeEditTextView/TextLine/Typesetter.swift

@@ -8,6 +8,11 @@
 import Foundation
 
 extension TextView {
+    override public func layout() {
+        layoutManager.layoutLines()
+        super.layout()
+    }
+
     open override class var isCompatibleWithResponsiveScrolling: Bool {
         true
     }